The present invention relates to a molding die of a laminated molding and manufacturing method of the laminated molding. More specifically, the present invention relates to a molding die of laminated molding having molding body made of synthetic resin with compressible surface member laminated thereto, and a manufacturing method of the laminated molding.
Conventionally, products made of synthetic resin are used for interior goods of an automobile, electric appliance components, household commodities etc.
Among the synthetic-resin-made products, an air-current control valve of an air conditioner for an automobile has flexible and compressible surface member for securing sealability thereof. Further, frame-shaped surface member as a sealing member is provided around an opening of an air-cleaner case for an automobile and peripheral portion of an inside of a refrigerator door in order to enhance air-tightness thereof
Such moldings having synthetic-resin-made molding body as a base and surface member integrated thereto can be manufactured by following methods:
(1) Attaching the surface member by adhesive or the like onto a surface of a molding body manufactured in advance by injection molding method or the like.
(2) Utilizing injection-molding method, where molten resin is injected into a die for molding the molding body integrally with the surface member after closing the die with the surface member being disposed therein (Japanese Patent Application Laid-open No. Hei 3-60297).
(3) Utilizing injection press molding method, where the surface member is disposed inside the die, and the molten resin is filled inside the die and is compressed by closing and clamping the die (Japanese Patent Application Laid-open No. Hei 5-83056).
(4) Enlarging clearance at a portion where the surface member is disposed in the internal space of the die (cavity) and providing a plurality of gate facing the enlarged portion. In molding the products, the surface member is disposed at the enlarged portion and molten resin is injected from the plurality of gate passing through the surface member to mold the molding body integrally with the surface member while controlling the molten resin flow (Japanese Patent Publication Laid-Open No. Hei 8-309786).
However, following disadvantages could occur according to the above methods.
According to the above (1) method, since the surface member has to be attached after shaping the molding products, lot of work is required and the productivity can be lowered.
According to method (2) and (3), since the surface member can be integrated simultaneously with the shaping step, the productivity can be enhanced.
However, when a surface member, especially compressible surface member such as polyurethane foamed sheet is partially laminated to the molding body, the molten resin flows toward a peripheral side of the surface member which is not abutted to inner surface of the die, i.e. exposed end of the surface member. Accordingly, the end of the surface member is likely to be caught in the molten resin, that is, the end of the surface member is turned over by the molten resin flow or buried in the resin and the entire surface member can cause position shift by being pushed off by the molten resin, thereby spoiling quality and appearance of the laminated moldings.
Since the method (4) is a multiple-gate type, molding failure such as weld mark and scorch is likely to be generated. And since the portion having the surface member of the molding body is made thick by enlarging inner space of the die, much resin is required thus being uneconomical, and generation of deformation and prolonged cooling time can be caused.
An object of the present invention is to provide a molding die of laminated molding and a manufacturing method of the laminated molding, where good quality and appearance can be obtained while improving productivity of the laminated molding and preventing molding failure.
The present invention is a molding die of a laminated molding for manufacturing a laminated molding having a molding body made of synthetic resin with a compressible surface member partially laminated thereonto. The present invention is characterized in having: a die body having a cavity for molding the laminated molding and being capable of attaching the surface member thereinside; a slide die structuring the die body and being advanceable and retractable relative to the cavity; and a flow-regulating portion provided to the die body for regulating a flow of a molten resin flowing toward the surface member.
In the present invention, since the flow-regulating portion for regulating the flow of the molten resin is provided to the die body, the molten resin can be prevented from directly flowing toward peripheral side of the surface member by making the flow-regulating portion regulate the flow of the molten resin flowing toward the surface member on the same plane as the surface member.
Accordingly, resin lap where the peripheral end of the surface member is turned over or buried in the resin by the flow of the molten resin, or position shift of the surface member by the resin flow can be prevented, thereby obtaining laminated moldings having good quality and appearance.
Further, since the flow of the molten resin can be controlled by the flow-regulating portion, it is not required to enlarge the portion of the cavity corresponding to the surface member as in the conventional method (method (4)), so that the portion of the molding body having the surface member laminated thereto can be prevented from being thick, thereby being economical for requiring fewer resin amount and being capable of preventing increase in cooling time and deformation of the molding body caused for becoming too thick.
Further, since a laminated molding having good quality can be obtained without employing multiple-gate method, molding failure such as weld mark and scorch can be prevented.
Since the surface member can be integrated simultaneously with the molding process of the molding body, the process for attaching the surface member can be omitted, thereby improving productivity.
Further, since the die body includes the slide die advanceable and retractable relative to the cavity, the resin pressure applied to the surface member can be lowered by retracting the slide die in filling the molten resin to prevent the molten resin from excessively permeating into the surface member, thereby preventing failures such as the surface member being fixed in a compressed condition and reducing damage caused on the surface member by the resin pressure.
Since the molten resin can be securely spread (filled) within the entire cavity by advancing the slide die after initiating to fill the molten resin, thereby obtaining molding body corresponding to the cavity configuration.
Foamed sheet made of resin such as polyurethane, polypropylene, polyethylene, laminated sheet having facing member such as other film integrated on at least one side of the foamed sheet etc. can be suitably used as the surface member.
The facing member to be integrated may be resin sheet or resin film made of PVC (polyvinyl chloride), thermoplastic elastomer etc., woven fabric and non-woven fabric.
The synthetic resin structuring the molding body as a base of the surface member may be thermoplastic resin such as polypropylene, polystyrene, polyethylene, ABS, polycarbonate, and compound of the thermoplastic resin with various additives.
The additives may be filler such as talc, mica, glass fiber, stabilizer for preventing deterioration by heat and light, coloring agent and so on.
In the above arrangement, the flow-regulating portion may preferably includes a plate-shaped flow-regulating plate, the flow-regulating plate being protrudable relative to the cavity.
By structuring the flow-regulating portion with the plate-shaped flow-regulating plate, the molten resin flowing toward the surface member can be introduced in a desired direction, thereby securely controlling the flow of the molten resin.
Since the flow-regulating plate is protrudable relative to the cavity, no recessed portion by the flow-regulating plate can be generated to the molding body by sinking the flow-regulating plate after the flow of the molten resin is decreased, thereby obtaining superior strength and appearance.
In this case, the flow-regulating plate is preferably continuously formed along a portion of a peripheral side of the surface member being exposed in the cavity.
Especially, the flow-regulating plate is preferably provided along a portion of the peripheral side of the surface member to be upstream of the molten resin flowing during injection.
In other words, since the resin lap at the peripheral end of the surface member and the position shift of the surface member is caused by the flow of the molten resin at the exposed portion of the peripheral side of the surface member, the peripheral side of the surface member can be covered by the die body and the flow-regulating plate by providing the flow-regulating plate along the exposed portion to be shut by the flowing molten resin, thereby further securely preventing the resin lap at the peripheral end of the surface member and the position shift of the surface member.
When the surface member is formed in a frame-shape, the flow-regulating plate is preferably provided along an inner peripheral side of the surface member.
Accordingly, the resin lap at the inner peripheral end of the surface member can be securely prevented even when the molten resin flows around inside the frame-shaped surface member.
When the surface member is formed in a frame-shape and is attached to a molding surface of the slide die, the slide die may preferably be formed in a frame-shape corresponding to the surface member, and an inner portion of the slide die of the die body may preferably structures the flow-regulating portion.
By forming the slide die in a frame-shape corresponding to the surface member, the surface member attached to the molding surface is sunk from the cavity so that the inner peripheral side of the surface member is covered by the inner portion of the slide die by retracting the slide die, thereby shutting the inner peripheral side of the surface member from the flowing molten resin.
Accordingly, since the portion to be the inner side of the slide die of the die body can also be used as the flow-regulating portion, no special structure is necessary for forming the flow-regulating portion, thereby simplifying the arrangement of the die body.
Alternatively, when the surface member is formed in a frame-shape to be attached to surround the slide die, the slide die may be formed in a block-shape corresponding to an opening of the surface member, the slide die structuring the flow-regulating portion.
In other words, by forming the slide die in a block-shape corresponding to the opening of the surface member, the peripheral side of the surface member attached surrounding the slide die can be covered by the slide die when the slide die is advanced, thereby shutting the peripheral side of the surface member from the flowing molten resin.
Accordingly, since the slide die itself can be used as the flow-regulating portion and no special structure for forming the flow-regulating portion is required, the arrangement of the die body can be simplified.
Another aspect of the present invention is a molding method for shaping a laminated molding having a molding body made of synthetic resin and a compressible surface member partially laminated thereto. The method includes the steps of: providing a molding die including a die body having a cavity thereinside for molding the laminated molding, a slide die structuring the die body and being advanceable and retractable relative to the cavity and a flow-regulating portion provided to the die body and for regulating a flow of a molten resin flowing toward the surface member; attaching the surface member to an inner surface of the die body; initiating injection of the molten resin to the cavity; and subsequently, advancing the slide die relative to the cavity.
In the present invention, the molten resin is injected to the cavity after attaching the surface member to the die body, the injected molten resin is flown and dispersed in the cavity, and is spread around the surface member.
At this time, as described above, since the die body has the flow-regulating portion, the flowing direction of the surface member can be restricted by the flow-regulating portion to be prevented from flowing toward the peripheral side of the surface member by providing the flow-regulating portion to regulate the flow of the molten resin flowing toward the surface member on the same plane as the surface member. Accordingly, the resin lap at the end portion of the surface member and the position shift of the surface member can be prevented, thereby obtaining laminated moldings having good quality and appearance.
Incidentally, the molten resin may flow beyond the flow-regulating portion in either injecting process or compressing process by advancing the slide die.
Since the flow-regulating portion allows to control the flow of the molten resin without enlarging the portion corresponding to the surface member in the cavity, the molding body can be prevented from being too thick, thereby preventing increase of resin amount, increase of cooling time and deformation of the molding body.
Further, since the laminated moldings with good quality can be obtained without employing multiple-gate method, molding failure such as weld mark and scorch can be prevented from generation.
After initiating injection of the molten resin, the slide die is advanced to reduce the cavity.
Since the cavity is enlarged before advancement of the slide die, the resin pressure applied to the surface member can be set low so that the molten resin can be prevented from excessively permeating in the surface member, thereby preventing failure such as fixing the surface member while being compressed.
Since the molten resin in the cavity is compressed by advancing the slide die, the molten resin can be completely spread in the cavity, thereby obtaining molding body corresponding to cavity configuration.
By solidifying the molten resin, the molding body having configuration corresponding to the cavity can be obtained and the surface member is integrated to the molding body.
Accordingly, the surface member can be integrated simultaneously with formation of the molding body, thereby achieving improved productivity.
In the above arrangement, simultaneously with advancing the slide die to the cavity, the flow-regulating portion is preferably retracted relative to the cavity.
Accordingly, no recessed portion by the flow-regulating portion is formed on the molding body, thereby obtaining good appearance.